The Core has two objectives. First, its mission is to provide state-of-the-art light microscopy instrumentation for the Lab of Receptor Biology and Gene Expression. Second, the Core provides support to anyone in the CCR who requires assistance with fluorescence imaging. Present work in the Core revolves around several established techniques: structural and morphometrical studies based on colocalization of different fluorescent markers by high-resolution and super-resolution techniques, 4D and 5D time-lapse analysis to follow how cellular components change over time and how cellular structures, nanomachines and proteins interact, fluorescence recovery after photobleaching to measure mobility and binding of cell molecules and fluorescence resonance energy transfer to measure molecular interactions in live or fixed specimens. For that the Core is maintaining and upgrading high-end commercial microscopes. Currently the Core maintains or is in process of acquiring wide-field optical sectioning workstations Delta Vision Core and Delta Vision Elite, Carl Zeiss LSM780 confocal microscope, Carl Zeiss SIM/dSTORM Elyra Super-resolution microscope. The Core is adapting Single Molecule Tracking techniques. A Single Molecule Tracking microscope is being built for the simultaneous multichannel molecule tracking. The Core is evaluating commercial 4D super-resolution instruments from Carl Zeiss, from VisiTech International and Applied Precision (GE Healthcare). The Core submitted a proposal for custom-building of the state-of-the art multifocus microscope for 4D/5D single molecule tracking, not available commercially.